This invention relates to an analytical chemistry method involving fluorescence, and more particularly to a method for determining the presence of chrysotile in a product sample.
Many manufactured products such as talc, construction materials, paints, and insulation have been known to contain various forms of asbestos, a form of impure magnesium silicate which has been implicated as a possible cause of cancer. Presently the form of asbestos which is the most abundant form found in the United States and which causes physiological concern is chrysotile, a hydrated magnesium silicate which may be represented as Mg.sub.3 Si.sub.2 O.sub.5 (OH).sub.4. Chrysotile has a serpentine structure with an infinite number of crosslinked (Si.sub.2 O.sub.5).sup.-2 portions and comprises a macroanion.
Because of the health concern, and the number of public and private buildings which have been constructed of materials which may contain chrysotile, a quick and reliable test for the detection of chrysotile is needed. Presently, if a bulk sample of material is found to contain 1% of more asbestos, abatement, disposal, or encapsulation of the material must be undertaken. It would be desirable to have a simple, reliable test which can be done on site to make the determination.
Several procedures have been developed for determining the presence of chrysotile. Two commonly known methods are X-ray diffraction and microscopic examination. However, these methods are not very reliable because X-ray diffraction is uncertain when working with samples containing low percentages of chrysotile, and microscopic examination often fails because the particles approach the limit of resolution of the instrument. Further, neither of these procedures is practical for field testing of bulk samples because of the equipment required and the need for trained technicians to operate that equipment.
Another procedure developed by Rose (U.S. Pat. No. 3,881,822) involves a spectrophotometric method for determining the chrysotile content in talc based on the preferential absorption of sulfonphthalein dyes by chrysotile but not by talc. However, this procedure is limited in that it relates only to determining the concentration of chrysotile in talc.
Other attempts have been made to determine the presence of chrysotile through a a fluorescent dye binding technique. (Albright et al. Microscope, pp. 267-280, (1982); Albright et al. R & D Report for National Science Foundation, Research on a Rapid and Simple Detection Method for Asbestos, 1980). When testing 26 different fluorescent organic dye compounds for binding affinity to chrysotile asbestos, two organic dyestuffs, Morin and 4,5-dihydroxy-naphthalene-2,7-disulfonic acid (DHNDS) were found to bind with chrysotile fibers at or near a pH of 11.4. However, the determination of which dyes will bind with chrysotile appears to be unpredictable.
Accordingly, there is a need to provide a rapid, simple, and accurate method for determining the presence of chrysotile in various product samples.